The vacuum-the-brush method requires only two items and a precondition:

The dirty brush

A dishwasher

A time when your spouse or significant other is not around

I definitely made sure my wife was not around to see this! I'm sure I would have received a horrified look and orders to stop and desist.

When the coast is clear...

Step 1. Empty the dishwasher. Only your wax brush should be in the dishwasher.

Step 2. Put the wax brush on the top shelf, bristle side down.

Step 3. Close the door and start the dishwasher on its normal cycle. Do NOT use the sanitize cycle - the water will be too hot for the brush! Do NOT use soap!

Step 4. After the washing and drying is complete, open the door and - voila! a super clean brush!

Caveat! The wood was slightly damaged by the hot water. If you look at the third picture, you'll notice bare wood and a little surface crack toward the bottom corner.

The "before" picture - an old nylon brush filled with wax,

Empty the dishwasher. Only your wax brush should be in the dishwasher. Put the wax brush on the top shelf, bristle side down. Close the door and start the dishwasher on it normal cycle. Do NOT use the sanitize cycle - the water will be too hot for the brush! Do NOT use soap!

The "after" picture: one very clean brush. But notice that some bare wood is showing, and there are some micro cracks in the surface of the wood.

I used my least favorite brush for this experiment, so if it was destroyed, I wouldn't really care. But it came out sparkling clean and only slightly damaged. Still, I'd use the dishwasher again only when a brush became so dirty or embedded with wax that the only alternative would be to throw it away. I recommend using one or more of the other three methods of brush cleaning, and only resort to the dishwasher when in dire need.